I used to think that some things didn't really matter. Following are things that I, now, have strong opinions about:
1) Power Supply. Batteries are the way to go.
2) Caps. Caps make a big difference.
3) You don't have to spend a lot of money for good speaker cables.
zman turned me on to Anti-Cables http://www.anticables.com/
. I paid about $70 for a set. Recently I hooked up my old cables, which cost about 10x what the anti-cables cost. I used anti-cables on the right channel, and the old cables on the left. The left sounded "muddy". I never realized this about the old cables - until I used both together.
Then I asked my wife, who is not really into music, to come into the room. She had no idea what I had done. I asked her to listen and tell me if she noticed anything. She said the right speaker sounded better.
Anyway, that is my opinion..FWIW.